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Chapter 4 - Installation and Wiring
PL-DU6900/PL-DU7900 User Manual
4.3.3 Connecting the DU’s Power Supply
Be sure to follow cautions explained here when connecting the power cord to the
DU’s Power Input Terminals.
• If voltage fluctuations are expected to
vary beyond the specified range, connect
a constant voltage transformer.
For information about
the specified voltage, refer to
2.1 General Specifications.
• Use a low-noise power supply both
between the lines and between the DU
and its ground. If there is still excess
noise, connect an insulating transformer
(noise-prevention type).
Be sure any constant or insulating
transformer used has a capacity of
70VA or more.
• Wire the power cords of the DU, I/O
devices, and power supply devices
separately.
• To improve noise immunity, it is recom-
mended to attach a ferrite core to the
power cord.
• Isolate the main circuit (high voltage,
large current) line, I/O signal lines, and
power cord, and do not bind or group
them together.
• To prevent damage from lightning,
connect a lightning surge absorber.
• Ground the lightning surge
absorber (E1) and the DU
(E2) separately.
• Select a lightning surge
absorber which will not
exceed the allowable
circuit voltage, even when
the voltage rises to the
maximum.
Constant
voltage
transformer
Twisted-pair
cable
DU
FG
Insulating
transformer
Twisted-pair
cable
DU
FG
Main power
source
DU
power
source
T1
T2
I/O power
source
DU
I/O
device
I/O
device
Main circuit
power source
Power
device
AC200V
AC 100V
DU
power
source
I/O power
source
DU
I/O
device
Main power
source
DU
Twisted-pair
cable
Lightning surge absorber
FG
E1
AC
E2
